N-chlorothio carbamates

ABSTRACT

N-chlorothio carbamates are produced by the reaction of sulfur dichloride and a carbamate having at least one hydrogen substituted on the carbamate nitrogen atom in the presence of a rate determining amount of an acid acceptor. The N-chlorothio carbamates are useful intermediates in the preparation of pesticides.

United States Patent Brown, deceased et al.

[ N-CHLOROTHIO CARBAMATES [75] inventors: Melancthon S. Brown, deceased,late of Berkeley, Calif.; Gustave K. Kohn, administrator, Berkeley,Calif.

[73] Assignee: Chevron Research Company, San

Francisco, Calif.

[22] Filed: May 8, 1972 [21] Appl. No.: 250,908

Related US. Application Data [63] Continuation-impart of Ser. Nos.88,105, Nov. 9, 1970, Pat. NO. 3,679,733, and Ser. NO. 189,732, Oct. 15.l97l.

[52] US. Cl... 260/3461 R, 260/479 C, 260/481 C,

424/300, 424/285 [51] int. Cl C07c 69/62, C07d 5/36 [58] Field of Search260/479 C, 481 C, 346.2 R

[56] References Cited UNITED STATES PATENTS 3,699,]22 l0/l972 Kohn260/3265 S Primary Examiner-.lohn D. Randolph AssistantExuminer-l3ernard Dentz Attorney. Agent, or Firm-G. F. Magdehurgcr; JohnStoner, J r.; Raymond Owyang 5 7 ABSTRACT 10 Claims, N0 Drawings cRossREFERENCE To RELATED APPLICATIONS This application isacontinuation-in-part of U.S.'Ser. No. 88,105, filed Nov; 9,1970, nowU.S. Pat. No. 3,679,733, and US; SerQNo. 189,732, filed Oct. 15, 1971.

DESCRIPTION OF THE INVENTION The N-chlorothio carbamates are representedby the formula (I): i

wherein R is a monovalent organo group of one to 20 carbon atoms,preferably one to 10 carbon atoms, and R is hydrogen or a hydrocarbylgroup of one to 10 carbon atoms. I I

The organo R is preferably free from non-aromatic u nsaturation,e.g.,from olefinic and acetylenic unsaturation. The R group is thereforesuitably saturated aliphatic, i.e., acyclic saturated aliphatic as wellas saturated cycloaliphatic, or is aromatic, preferably mononuclear rbinuclear aromatic, and is a hydrocarbyl group containing only atoms ofcarbon and hydrogen or is a substituted hydrocarbyl group containing, inaddition to atoms of carbon and hydrogen, other atoms such as oxygen,sulfur, nitrogen and halogen,- particularly halogen of atomic number offrom 9 to 53 inclusive, i.e., fluorine, chlorine, bromine or iodine,which additional atoms are present in functional groups such as alkoxy,aryloxy, carboalkoxy, alkanoyloxy,

halo, trihalomethyl, cyano, nitro, dialkylamino, sulfonylalkyl, and likegroups having no active hydrogen atoms.

The R groups are preferably hydrocarbyl groups containing only carbonand. hydrogen or hydrocarbyl groups substituted with halogens, nitrogroups, alkoxy groups of one to five carbon atoms, alkylthio groups ofone to three carbon atoms, or dialkylamino groups in which thealkyl-groups contain individually one to three carbon atoms. Aparticularly preferred R group is a 2,3-dihydro-7-benzofuranyl grouprepresented by the formula (ll):

I alkoxy, alkylthio and dialkylamino substituted aromatic groups areexemplifiedby 2-fluorophenyl, 3-

fluorophenyl, 4-chlorophenyl, 2,4-difluorophenyl, 3,4-

difluorophenyl, 2,4 -dichlor ophenyl, 3,4- dichlorophenyl,Z-nitrophenyl, 3-nitrophenyl, 4- nitrophenyl, 3,5-dinitrophenyl,4-methoityphenyl, 2- isopr'opoxyph'enyl, 3-methylthiophenyl; 2-fluoro-4- methylphenyl, "2-chloro-3,4-dimethylphenyl,3,5-dichloro-4-methylphenyl, 2-nitro-4-ethylphenyl, 4-nit'robenzyl,2-fluorobenzy1, 4-methoxybenzyl, 4-methylthiobenzyl,3,5-dimethyl-4-methylthiophenyl,2,3-dihydro-2,2-dimethyl-7-benzofuranyl, 4- dimethylaminophenyl, and3-methyl-4- dimethylaminophenyl.

illustrative hydrocarbyl R and R groups are alkyl groups of one to sixcarbon atoms, such as methyl, ethyl, propyl and hexyl, and aromaticgroups such as phenyl, aralkyl or alkaryl groups of seven to 10 carbonatoms, as illustrated above. The preferred R and R groups are alkyl ofone to four carbon atoms, especially methyl.

Representative compounds include N-chlorothio-N- 'meth'yl-ovmethylcarbamate, N-cIhlorothio-N-methyl- O-phenyl bamate,

O-butyl carbamate, N-chlorothio-N-methyl-O-pchlorocyclohexyl carbamate,N-chlorothio-N-methyl- O-tetrachloroethyl carbamate,N-chlorothio-N-methylcarbamate, N-chlorothio-N-methyl-O-(anaphthyl)carbamate, N-chlorothio-N-methyl-O-benzyl carbamate,N-chlorothio'N-methyl-O-p-chlorobenzyl carbamate,Nchlorothio-N-methyl-O-(3-secbutylphenyl) carbamate,N-chlorothio-Nmethyl-O-pt-butylphenyl carbamate,N-chlorothio-N-ethyl-O-(B- naphthyl) carbamate, N-chlorothio-N-methyl-O-fluorophenyl carbamate, N-chlorothio-N-methyl-O- chlorophenyl carbamate,N-chlor othio-N-methyl-3,4- dichlorophenyl carbamate,N-chlorothio-O-pfluorophenyl carbamate, N-chlorothio-N-methyl-0-(2,3-dihydro-2,2-dirnethyl-7-benzofuranyl) carbamate,N-ehlorothiorN-methyl-O-(2-isopropoxyphenyl) carbamate,N-chlorothio-N-methyl-O- (2,3,5-trimethylphenyl) carbamate,N-chlorothio-N- methyl-O-(2,4,5carbamate, N-chlorothio-N-methyl-O-(3-methyl-4-di-methylaminophenyl) carbamate, N-chlorothio-N-methyl-O-(3,5-dimethyl- 4-methylthiophenyl) carbamate,N-chlorothio-N- phenyl-O-isopropyl carbamate, N-chlorothio-N-3-chlorophenyl-(Oisopropyl) carbamate, N-chlorothio-N-methyl-O-(2-chloro-3,4-dimethylphenyl) carbamate,N-chlorothio-N-methyl-O-(4-methy1-3,6-di-tbutylphenyl) carbamate,N-chlorothio-N-methyl-O-( anaphthyl) carbamate, and N-chlorothio-N-(4-chlorophenyl-O-isopropyl carbamate.

Representative N-chlorothio compounds wherein R is a2,3-dihydro7-benzofuranyl group are O-2,3-dihydro-7-benzofuranyl-N-chlorothio carbamate, 0- 2,3-dihydro-Z-methyl-7-benzofuranyl-N-methy1-N-chlorothio carbamate,0-2,3-dihydro-2-ethy1-7-benzofuranyl-N- methyl-N-chlorothio carbamate,O-2,3-dihydro-2,2- diethyl:7-benzofuranyl-N-methyl-N-chlo'rothio car-O-2,3-dihydro-2,2-dimethyl- 7-benzofuranyl-N-ethyl-N-chlorothiocarbamate, O-2,3-dihydro-2-phenyl- 7-benzofuranyl-N-methyl-N-chlorothiocarbamate, 0- 2,3-di-hydro-2,2-dimethyl-7-benzofuranyl-N-phenyl-Nchlorothio carbamate, 0-2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N-phenyl-N-chlorothio carbamate, 0-

3 2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N- cyclohexyl-N-chlorothiocarbamate, O-2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N-benzyl-N-chlorothio carbamate, andO-2,3-dihydro-2,2-dimethyl-7-benzofuranyl-N-methyl-N chlorothiocarbamate.

It is appreciated, of course, that the in compounds illustrated above,the groupsprefixed by N, refer to the w Formula I).

The N-chlorothio carbamates are prepared in accordance with'thefollowing reaction:

/SCl Q R--i:-N 13-1101 y y wherein R and R have the same significance aspreviously definedand B is an acid acceptor.

The acid acceptor is an organic base such as a pyridine compound or atrialkylamine compound. Suitable pyridine compounds are pyridine andpyridine compounds of six to carbon atoms and of l to 2 alkyl groupssuch as Z-methylpyridine, 2-ethylpyridine, 3- methylpyridine,.3.5-dimethylpyridine. and 2- butylpyridine. Suitable trialkylamines arethose wherein the alkyl group contains individually l te 4 carbon atoms,such as trimethylamine, triethylamine, tripropylamine and tributylamine.

Generally, commerically available sulfur dichloride of reasonablepurity, e.g., greater than 90-98 percent purity, is suitably employed.The sulfur dichloride may contain small amounts of an inhibitor such astributylphosphate or triethylphosphate.

The sulfur dichloride and the carbamate compound are employed insubstantially equimolar amounts, e.g., the molar ratio of sulfurdichloride to the carbamate compound generally varies from about 1.5:1to 1:15, although molar ratios of sulfur dichloride to the carbamatecompound of 1.421 to l.'l:l are preferred. The molar ratios of acidacceptor to sulfur dichloride is also substantially equimolar, e.g., themolar ratio of acid acceptor to sulfur dichloride varies from about1.2:] to l:l.2, although molar ratios of acid acceptor to sulfurdichlorideof 1:1 to 1212 are preferred.

in orderto produce the N-chlorothio carbamate compounds of the inventionin high yield, it is essential to react the carbamate and sulfurdichloride in the presenceof a limited amount of free, uncomplexed acidacceptor. This is suitably accomplished by the addition of the acidacceptor to a substantially equimolar mixture of the carbamate and thesulfur dichloride so that the moles of free acid acceptor to the totalmoles of carbamate reactant and N-chlorothio carbamate is less than0.2:1, preferably less than 0.111, and more preferably less than 0.05:1.In other words, during the course of the reaction between the sulfur(ii-chloride and the carbamate reactants, there should be at least 5moles of the carbamate reactant and the N-chlorothio carbamate productper mole of acid acceptor which is not complexed with hydrochloric'acid.

Provided that the reaction is conducted with the restricted amount ofacid acceptor indicated above, the contacting of the acid acceptor withthe mixture of the carbamate and the sulfur dichloride can be conductedby a variety of procedures. In one modification, the acid acceptor isadded in increments, e.g., dropwise, in an inertdiluent, if desired,'toa mixture of the carbamate and sulfur dichloride in an inert diluent. Inanother modification, the acid acceptor is added continuously to amixture of the carbamate and sulfur dichloride in an inert diluent.

Suitable inert diluents for the reaction include alkanes of five to 10carbon atoms, such as hexane, isooctane and decane; aromatic compoundssuch as benzene and chlorobenzene; oxygenated hydrocarbons such asacyclic alkyl'ethers, e.g., dimethoxyethane and dibutyl ether; andcycloalkyl ethers, e.g., dioxane, tetrahydrofuran and tetrahydropyran.Other suitable diluents include nitriles such as acetonitrile andpropionitrile and dialkylamide such as dimethylformamide. Preferreddiluents are chlorinated hydrocarbons of one to two carbon atoms, suchas methylene dichloride, chloroform, carbon tetrachloride and ethylenedichloride. Generally, the amount of diluent employed ranges from 1' to50 moles per mole of sulfur dichloride.

The reaction is suitably conducted at a temperature between 20C. and theboiling point of the diluent, although temperatures between 0C. and 50C.are preferred. The reaction is conducted at or above atmosphericpressure.

The preparation of the N-chlorothio carbamates is illustrated by thefollowing examples.

EXAMPLE I N-Chlorothio-N-methyl-O methyl carbamate O-methyl-N-methylcarbamate, 17.8 g (0.2 mole) was dissolved in 200 ml methylenedichloride. Sulfur dichloride, 26.7 g (0.26 mole) was added dropwise tothe solution. Pyridine, 17.4 g (0.22 mole) was added to the solution at2530C. After theaddition was complete, the pyridine hydrochlorideproduct was filtered from the reaction mixture. Evaporation of thesolvent and distillation under reduced pressure gave the N-chlorothio-N-methyl-O-methyl carbamate product. The nuclear magneticreasonance spectrum of the product showed a sharp singlet at 3.45 ppm(relative to tetramethylsilane) for the N-methyl group. The N- methylgroup of the O-methyl-N-methyl carbamate starting material appeared as adoublet at 2.9 ppm (relative to tetramethylsilane).

EXAMPLE 2 N-Chlorothio-N-methyl-O-(3-sec-butylphenyl) carbamate Nmethyl-O-(3-sec-butylphenyl) carbamate, 20.7 g (0.1 mole) was dissolvedin ml methylene chloride. Sulfur dichloride, 11.3 g (0.11 mole) was thenadded to the solution at about 25C. Pyridine, 9.48 g (0.12 mole) wasadded dropwise to the solution at a temperature of 2530C. The resultingpyridine hydrochloride product was filtered from the reaction mixture togive a solution of butylphenyl) carbamate product in methylene chloride.The nuclear magnetic resonance spectrum of the solution showed a sharpsinglet at 3.4 ppm (relative to tetramethylsilane) for the N-methylgroupof the product.

EXAMPLE'B N-Chlorothio-N methyl-O-(oz-naphthyl) carbamateN-chlorothio-N-methy1-O-(3-sec- N-methyl-O-(a-naphthyl) arba t 4 g ()5l0 tions and resultsare tabulated in Table 1.

' TABLEI REACTANT(MOLES) BlS-CARBAMOYL PHENYLDITHIO RUN MODE OF ADDITIONCARBAMATE SCI; BASE SULFlDE CARBAMATE l I SCl, to carbamate/base 0.1 0.11 0.12 i 53.2 37 2 Carbamate/base to SC], 0.1 0.1 l 0.12 25.3 1 27.4 3Base to, carbamate/SCI, 0.1 0.1 l 0.12 8.6 63.2 4 Base to carbamate/SCI,v 0.1 0.13 0.11 0 71.3

mole) and sulfur dichloride, 5.7 g (0055 mole) were UTILITY slurried in50 ml methylene dichloride. Pyridine, 4.7 g (0.06 mole) was then addeddropwise at -30C. After the addition was complete, thepyridinehydrochloride wasfiltered from the. reaction mixture to give a solutionof the N-chlorothio-N-methyl-O-(anaphthyl) carbamate product inmethylene dichloride.

The nuclear magnetic resonance spectrum of the product showed a sharpsinglet at 3.6 ppm (relative to tetramethylsilane) for the N-methylgroup of the product.

v EXAMPLE 4 N-Chlorothio-N-methyl-O-(2,3-dihydro-2,2-dimethyl-7-benzofuranyl) carbamate Pyridine, 9.8 g (0.12 mole) was addeddropwise to a mixture of 22. lv g (0.1 mole) N-methyl-O.-(2,3-dihydro2,2-dimethyl-7-benzofuranyl) carbamate .at 25-30C.

The production of the N-chlorothio carbamate derivative was indicatedvby the nuclear magnetic resonance spectrum of the reaction mixture whichshowed asharp singlet at 3.7 ppm (relative to tetramethylsilane). forthe N-methyl group of the N-chlorothio-N-methyl-O-(2,3-dihydro-2,Z-dimethyl-7-benzofuranyl) carbamate product.

A small amount of bis-[O(2,3-dihydro-2,2-dimethyl-7-benzofuranyl)-N-methyl carbamoyl] sulfide is. produced as a by-productof the above reaction. However, the preferred method for preparing thisbis-carbamoyl sulfide is by the process of U.S. Ser. No. 88,105 of M. S.Brown and G. K. Kohn, filed Nov. 9, 1970, now U.S. Pat. No. 3,679,733.

EXAMPLE 5 N-phenyldithio-O-(3-sec-buty1phenyl) The N-chlorothiocarbamates are useful intermediates for the preparation of pesticides.For example, the N-chlorothio carbamates can be reacted with alcohols,mercaptans, ureas, carbamates, amines,'amides, anilides, and othercompounds have active hydrogen atoms to give the correspondingsubstitution product (and hydrochloricacid) by the conventionalprocedures employed for the reaction of saulfenyl halides and compoundshaving active hydrogen atoms, as disclosed, for example, by E. Kuhle,Synthesis, 617 (1971).

By way of illustration, representative N-chlorothio carbamates of theinvention are converted to N-dithio carbamate compounds in the followingexamples:

EXAMPLE 6 Preparation of N-methyl-N-phenyldithio-O-(m-secbutylphenyl)carbamate A solution of about 0.1 mole N-chlorothio-N-methyl-O-(3-sec-butylphenyl) carbamate in ml methylene dichloride was preparedas described in Example 2.

A solutionof 11 g 0.1 mole) benzenethiol and 7.9 g (0.1 mole) pyridinein 20 m1 methylene dichloride was added dropwise to the solution ofN-chlorothio carbamate at 0C. over a period of 5 minutes. Ten minutesafter the addition was complete, the reaction was washed with water,washed with sodium bicarbonate solution, dried over magnesium sulfateand evaporated under reduced pressure to give 32.5 g of an oil residue.The oil was chromatographed over silica gel (hexane and ethylether-hexane eluents) to give the N-metl1ylcarbamate product. Elementalanalysis for C,,,H ,NO S showed:

Cale. Found An acetone solution of the N-phenyldithio carbamate productcontaining a small amount of nonionic emulsifier was diluted with waterto 500 ppm. Cabbage leaf sections were dipped in the solution and dried.The sections were then infested with cabbage looper larvae (Trichoplusiani); After 24 hours, there was a 100 percent mortality of the cabbagelooper larvae.

EXAMPLE 7 Preparation of N-methyl-N-methyldithio-O-( m-secbutylphenyl)carbamate A; solution of about 0.1 mole of N-chlorothio-N- methyl--(3-sec-butylphenyl) carbamate in 100 ml of methylene dichloride wasprepared as'described in Example 2. 1 I

A solution of 4.8 g (0.1 mole) methyl mercaptan and 7.9 g (0.1 mole)pyridine in 20 ml methylene dichloride was added dropwise to thesolution of the N-chlorothio carbamate at 0C. over a period of 5minutes. Ten minutes after the additionwas complete, the reactionmixture was washed with water, washed with sodium bicarbonate solution,dried over magnesium sulfate and evaporated under reduced pressure toyield 27 g of an oil. The oil was chromatographed on silica gel (benzeneeluent).to give the N-methyl-N-methyldithio-O- ('3-sec-butylphenyl)carbamate product. The nuclear singlet at 2.78 ppm (relative totetramethylsilane) for the N-methyldithio group and a singlet at 3.4 ppm(relative to tetramethylsilane) for the N-methyl group. Elementalanalysis for C H NO s showed;

Calc. u Found By the procedure used'in Example 6, methyldithio carbamateproduct was found to give 100% control of cabbage looper larvae,

EXAMPLE 8 Preparation of N-phenyldithio-N,O-dimethyl carbamate A 17.4 g(0.22 mole) sample of pyridine was added dropwise to a solution of 19.8g (0.2 mole) N-methyl- O-methyl carbamate and 26.8 g (0.26 mole) sulfurdimixture was washed with water, washed with sodium bicarbonatesolution, dried over magnesium sulfate and evaporated to give 37.3 g(89.5 percent yield) of the N-phenyldithio-N-methyl-O-methyl carbamateproduct. A small sample was purified by column chromatogmagneticresonance spectrum of the product-showed a I raphy for elementalanalysis, which showed:

Cale. Found lt is claimed: l. N-chlorothio carbamates of the formula SClwherein R is an organo group of one to 20 carbon atoms and free fromnon-aromatic unsaturation selected from (1) alkyl, (2) cycloalkyl, (3)phenyl, (4) naphthyl, (5) alkylphenyl, '(6) alkylnaphthyl, (7)phenalkyl, (8) naphthalkyl, (9) phenyl, naphthyl, alkylphenyl,alkylnaphthyl, phenylalkyl or naphthalkyl substituted with halogens ofatomic number 9 to 35, nitro groups, alkoxy of one to five carbon atoms,alkylthio of one to three carbon atoms or dialkylamino in which thealkyl group contains individually 1 to 3 carbon atoms, and (8)2,3-dihydro-7-benzofuranyl of the formula wherein R individually ishydrogen or alkyl of one to six carbon atoms; and R is hydrogen or analkyl group of one to 10 carbon atoms.

2. The carbamate of claim 1 wherein R is alkyl of one to six carbonatoms.

3. The carbamate of claim '2 wherein R is methyl. 4. The carbamate ofclaim 3 wherein R is alkyl. 5. The carbamate of claim 4 wherein R ismethyl. 6. The carbamate of claim 3 wherein R is phenyl, naphthyl,alkylphenyl, alkylnaphthyl, phenalkyl or naphthalkyl.

7. The carbamate of claim 6 wherein R is naphthyl.

8; The carbamate of claim 6 wherein R is m-secbutylphenyl.

9. The carbamate of claim 2 wherein R is represented by the formula.l0.'The carbamate of claim 9 wherein R and the R groups are methyl.

1. N-CHLOROTHIO CARBAMATES OF THE FORMULA
 2. The carbamate of claim 1wherein R1 is alkyl of one to six carbon atoms.
 3. The carbamate ofclaim 2 wherein R1 is methyl.
 4. The carbamate of claim 3 wherein R isalkyl.
 5. The carbamate of claim 4 wherein R is methyl.
 6. The carbamateof claim 3 wherein R is phenyl, naphthyl, alkylphenyl, alkylnaphthyl,phenalkyl or naphthalkyL.
 7. The carbamate of claim 6 wherein R isnaphthyl.
 8. The carbamate of claim 6 wherein R is m-sec-butylphenyl. 9.The carbamate of claim 2 wherein R is represented by the formula
 10. Thecarbamate of claim 9 wherein R1 and the R2 groups are methyl.